Aqueous inks are frequently used as printing or writing inks for the ease of manufacture and handling. For example, with the recent development and spread of computers, printers have also been spreading, and aqueous inks are made frequently use of in such printers.
The inks for an ink jet printer, one of typical printers, usually comprise a water-soluble dye capable of dissolving in water so as to avoid clogging of nozzles with the ink. Inks comprising a water-soluble dye hardly obstruct the nozzles but, in turn, the resulting printed image has poor waterfastness.
Therefore, the composition of inks is of importance to improve waterfastness of printed images.
In order to improve the waterfastness of the inks for ink jet recording, it has been proposed to use ink comprising a pigment (see Japanese Patent Laid-Open Nos. 4-28776, 4-189876, 4-359071, and 4-359072), a non-aqueous medium (see Japanese Patent Laid-Open No. 4-261478), or a dye having excellent waterfastness (see U.S. Pat. No. 4,963,189).
However, use of a pigment in inks tends to incur a reduction in chroma of printed images and to cause clogging of the nozzles. Further, a pigment has insufficient fixation properties onto paper or an OHP (overhead projector) sheet, so that the printed image has insufficient record preservability. Neither has the other proposals succeeded in providing inks fully satisfying all the requirements, such as anti-blurring properties, waterfastness, and fixation.
Accordingly, an object of the present invention is to provide an aqueous ink which is prevented from blurring and provides printed images exhibiting improved waterfastness and improved fixation.
Another object of the present invention is to provide an aqueous ink which is particularly useful as an ink for ink jet recording.